1. Field of the Invention
The present invention relates to a DNA vaccine consisting of a vector expressing a part or the whole of a polypeptide regulating production of an inflammatory cytokine, a pharmaceutical composition comprising the DNA vaccine, and a method of preventing or treating inflammatory diseases by using the pharmaceutical composition.
2. Related. Art
Cytokines are biologically active substances produced by various cells including immune cells. It is also known that one cytokine shows various bioactivities and participates in biological defense such as antiviral action and antitumor action by enhancing immune cells such as lymphocytes, macrophages, NK cells and neutrophils. Cytokines have a feature of acting on one another to contribute to maintenance of homeostasis for biological defense. However, it is noted that cytokines have an action of inducing inflammations and participate in formation of pathologic conditions of various diseases such as rheumatoid arthritis, autoimmune diseases, allergic diseases, fulminant hepatitis, malignant tumors, diabetes and arteriosclerosis. As these diseases become more advanced, cytokines, particularly called inflammatory cytokines such as interleukin-1 (IL-1), interleukin-2 (IL-2), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) become induced and detected in blood and tissue (Jiro Imanishi, “Igaku No Ayumi” (Development of Medicine), 181, 750 (1997)).
On one hand, macrophage migration inhibitory factor (abbreviated hereinafter as “MIF”) found in 1966 (Bloom B R, et al.: Science 153, 80 (1966)) as a factor to inhibit migration of macrophages in a culture supernatant of lymphocytes from a guinea pig activated by antigen sensitization has been studied for a long time because thereafter its various functions such as isomerase activity, oxidoreductase activity etc. were rediscovered and MIF was found widely in living things ranging from nematodes to vertebrates. At present, MIF is known to be a special peptidic biological active substance which is involved in both natural immunity and acquired immunity for production of cytokines participating in biological defense and which has a plurality of enzyme activities in the same molecule (Rosengren, E., et al.: Mol. Med. 2, 143-149 (1996), Kleemann, R., et al.: J. Mol. Biol. 280, 85-102 (1998)). However, there is no report showing the relationship between these enzyme activities and immunity.
Usually, cytokines are expressed by transcription from genes in the intranuclear genome upon induction with stimulation and produced as proteins one by one by immunocytes. On the other hand, MIF is characterized in that it is previously stored like hormone in cells, and upon external stimulation with an endotoxin or the like, is secreted from a plurality of local tissues including an anterior pituitary gland. Macrophages or T cells stimulated with MIF are not suppressed by glucocorticoids, so MIF is reported to be a biologically active substance counteracting the immunoreaction suppressed by glucocorticoids (Calandra, T,. et al.: Nature 377, 68-71 (1995)).
It is reported that MIF receptors occur on cell surfaces; but this is not necessarily evident. In this relation, it is known that MIF is incorporated for example by endocytosis into cells and binds to Jab1 that is a protein in the cytoplasm (Kleemann, R., et al.: Nature 408, 211-216 (2000)).
Recently, DNA vaccine is developed by the advancement of genetic engineering technology. The DNA vaccine is generally a vaccine using a recombinant plasmid, and a recombinant plasmid comprising a DNA encoding a target antigen is administered to the living body, whereby an amino acid sequence with antigenicity, encoded by the DNA, is expressed in the living body, and an immunoreaction is induced by this amino acid sequence. However, even if a certain specific plasmid DNA is administered to the living body, the degree of immunoreaction induced is not constant, and the degree of immunoreaction varies depending on the type of test animal, the type of DNA and an inoculation method, and it is generally difficult to predict whether the DNA plasmid is useful as DNA vaccine. Under these circumstances, it is attempted to use, for example, interleukin-5 (IL-5) as DNA vaccine for asthma etc. (Hertz, M., et al.: J. Immnol. 167, 3792-3799 (2001)).